MR Lymphangiography

Abstract

The imaging of lymphatic system is much difficult than that of blood circulation due to several reasons. Firstly, lymphatic vessels are slender, fragile, and transparent. Thus, to approach lymphatic vessel and deliver contrast directly is not easy. Secondly, the diameters of lymphatic vessel are small and the wall has less smooth muscle cell that leads to a weak contraction at a low rhythm. Lymph flow at a lower speed is a nonconstant stream under normal condition. Therefore, lymphatic pathway may not always be visualized during imaging. Thirdly, the composition of lymphatic system network is more complex than the blood system. There are around 600 of lymph nodes in human body, which distribute between every two or more efferent and afferent lymphatic vessels [1]. The commonly used lymphoscintigraphy with isotopic contrast agent has insufficient resolution to accurately outline the internal anatomy of lymph node and lymphatic vessels. Lymphangiography using iodine oil agent, which is capable of visualizing the lymphatics, is no longer routinely performed because it is highly invasive and difficult to perform and also can lead to life-threatening complications. As a new diagnostic test, 3D high-resolution MR lymphangiography (MRL) has been proven to be useful in the diagnosis of peripheral lymphatic system disorders in recent years [2–5]. Around 2000 patients have been examined in the author’s clinic since 2007. MR lymphangiography with gadobenate dimeglumine quickly and sufficiently visualizes the lymphatic pathway and lymph nodes draining from the intracutaneously injection sites in lymphedematous limbs and gives both morphological and functional assessments of tested lymphatic system.